Inductance system



g- 1931- L. A. GEBHARD INDUCTANCE SYSTEM 2 Shee ts-Sheet 1 Filed Dec.22, 1928 Gel-wizard o vide an inductance Patented Aug. 11, .1931

' um'rao s rrvras PATENT? OFFICE ammo, or wasnmo'roir, msrarc'r orconumnranssrcuon no men more, me. or-mxoun. r. a coaroaarrou or DELAWARE4 mnuc'rancu' srs'rmm Application died December 22, 1928. Serial No.327,884.

An object of my invention is to rovide an adjustable inductance wherebya justments of the frequency characteristics may be easily and readilaccomplished. 7

Another ob ect of my invention is to proarticularly adapted to be emploedin com ination with balanced thermionic tube circuits.

Still another object of my invention is to provide an inductance systemadapted to be employed in combination with balanced thermionic tubecircuits whereby adjustments of the frequency characteristics do notdestro the symmetrical or balanced condition of t e associated circuits.

Other and further objects of my invention reside in the structuralfeatures of the inductance system of my invention, a betterunderstanding of which can be had from the specification following andby referring to the accompanying drawings wherein:

Fi re 1 is a schematic circuit diagram showing the inductance system ofmy invention and Figs. 2, 3 and 4 are diagrammatic representationsshowing structural features of my invention.

In thermionictube circuits wherein the several thermionic tubes areconnected in electrically balanced arrangements it is essential thatthis balanced arran ement be maintained irrespective of ad ustments inthe frequency characteristics of the circuits. Fig. 1 is a schematiccircuit diagram showing such a balanced circuit arrangement. Thermionictubes 1 and 2 have cathodes 3 and 4, control electrodes 5 and 6,shielding anode electrodes 7 and 8 and anodes 9 and 10 respectively.Shieldin anode electrodes 7 and 8 are connected wit source of energy 11.

Source of energy 11 may be connected with electrodes 5 and 6 as isordinarily the practice when three electrode thermionic tubes areemployed. The output circuits of thermionic tubes 1 and 2 compriseinductance 12,

'the common cathode connection from the tubes established at or near theelectrical center 13 of inductance 12. A. capacity 14 is usuallyconnected in parallel with -inductance 12 although the capacity of therespective turns comprising inductance 12 usually constitutes suflicientcapacity. The capaclty may be simultaneously varied with adjustments inthe frequency characteristics of inductance 12. Inductance 12 may be inelectrical relation with any suitable load circuit 15. Load circuit-15may comprise thermionic tube amplifier circuits, a space radio radiatingsystem or a wired radio system. Associated with and electricallyconnected to the electrical center connection 13, are provided contactmembers 16 and 17 These members may be adjustably positioned along thelength of inductance 12 thereby shunting the necessary portion of theinductance to obtain the desired frequency characteristics.

Assuming that the frequency characteristics of thermionic tubes 1 and 2correspond, connectors 16 and 17 would be spaced equidistant fromelectrical center connection 13. Adjustments to obtain other frequencycharacteristics would be obtained and the symmetr or balance retained bycausing contact mem ers 16 and 17 to be moved in opposite directions oraway from contact 13. The method employed to accomplish this is betterunderstood by referring to Figs. 2 3 and 4.

Fig. 2 shows a side elevation and the structural features of theinductance system of my invention. The inductance proper, comprisessuitable metallic ribbon or tubing 12 wound in the form of a helix, andsupported by insulating members 22. Insulating members 22 are supportedby end'members 23 and 24. Contact members 16 and 17 are secured tometallic arms 18 and 19 respectively and bear against the turns ofinductance 12. Arms 18 and 19 are associated with shafts 20 and 21respectively Shaft 21 comprises a len th of tubing surrounding; shaft 20and mova ble in respect thereto. S aft 20 is supported by a suitablebearing in end member 23. Shaft 21 is supported b a suitable bearing inend member 24. he ends of shafts 20 and 21 are provided with gears 25and 26 respectively which are secured thereto. Gear 25 meshes with gear27 and the latter with gear 28. Gear 28 is POSI- tioned on a commonshaft which also supports gear 29. Gear 29 meshes with gear 26. Asuitable end plate 30 rovided with the necessary bearings, may e interal with end member 24 or supported there rom by suitable supportingmembers 31. A control member 32 is secured to one end of shaft 20. Thepanel 33 of the transmitter may be provided with a window 36 by means ofwhich the o erator may observe the indicated position o the contactmembers.

The relative length of the inductance shunted ma be determined byobserving the reading on ial35. Dial 35 may be provided with suitablegear mechanism 34 and the latter mechanically connected for movementcorresponding to the rotary movement of shaft 20. The rotation ofcontrol member 32 in a clockwise direction causes gear to move in aclockwise direction, gear 27 to move in a counter-clockwise direction,gears 28 and a 29 in a clockwise direction and gear 26 to move in acounter-clockwise direction. Since arms 18 and 19 are secured to shafts20 and 21 respectively and must rotate therewith, contact members 16 and17 are rotated around the turns of inductance 12 in opposite directions.Inductance 12, being wound in a helicalmanner causes contact members 16and 17 to move away from each other. Contact members 16 and 17 areelectrically connected and hence the separation therebetween constitutesthe portion of the inductance shunted out of the circuit.

Fig. 3 of the accompanying drawings shows an end elevational view of theinductance system of my invention. The tubing or ribbon 12 is supportedby members 22-22a. Contact members 16 and 17 may consist of springmetallic material. Arm members 18 and 19 are rotatable with shafts 20and 21 respectively and movable horizontally along the lengths thereof.Fig. 4 shows a modification of the inductance system of my invention.Reference characters employed in this illustration correspond to thoseof Figs. 1, 2 and 3. Control member 32 is here shown secured to shaft44. Contact members 16 and 17 are associated with metallic arm members18 and 19 respectively. Metallic arm members 18 and 19 are mounted onshafts 20 and 21 respectively. Shafts 20 and 21 are common to contactwasher 42 which is electrically connected to the electrical center ofinductance 12 by connecting member 41.

Gear 25 is secured to shaft 20 and gear 26 is secured on shaft 21. Gear25 engages with gear 27 and the latter engages with gear 28. Gear 26engages with gear 29. Gears 28 and 29 are secured on a common shaft 44controllable by control member 32. Gear 34 is secured to shaft 44 and ismechanically connected to indicating dial 35.

Dial 35 may be suitably calibrated and positioned in such a manner as tobe visible throu h window 36 inserted in panel 33.

In ig. 4, assuming that a balanced thermionic tube system is connectedwith inductance 12 similar to the schematic circuit arrangement shown inFig. 1, the anodes 9 and 10 of thermionic tubes 1 and 2 would beconnected with terminals 9a and 10a of inductance 12. The electricalcenter of inductance 12 connected to terminal 13a, would be connected tothe common cathode circuit of the thermionic tubes. Thus the portion ofinductance 12 between terminals 13a and 9a would constitute the outputcircuit of thermionic tube 1. The portion of inductance 12 betweenterminals 13a and 10a would constitute the output circuit of thermionictube 2. Since terminal 13a is electrically connected to shafts 20 and 21by means of connectin members 4142 and contact members 16 an 17 areelectrically connected to shafts 20 and 21 respectively, it follows thatthe efl'ective inductance in the output circuit associated withterminals 13a-9a comprises that portion of the inductance includedbetween contact member 17 and terminal 9a. Likewise the effectiveinductance in the output circuit associated with terminals 13a and 10acomprises that portion of the inductance included between contact member16 and terminal 10a.

A rotary motion transmitted to control member 32 causes contact members16 and 17 to move toward or away from terminal 13a thereby causing theeffective inductance included between terminals 13a and 9a tosimul'raneously increase or decrease with the increase or decrease ofthe effective inductance included between terminals 13a and 10a. Asecond position of contact members 16 and 17 is represented by dottedlines 16a and 17a respectively. It is obvious that a balanced circuit isobtained irrespective of changes in the frequency characteristicsdesired.

I realize that many modificationsof the inductance system of myinvention are ossible without departing from the spirit 0 my invention.Many modifications of my invention include gear and mechanical arrangements other than those shown in the accompanying drawings. It is to beunderstood that my invention shall not be limited to the foregoingspecification or to the accompanying drawings but only as defined in theappended claims.

What I claim as new and desire to secure by Letters Patent of the UnitedStates of America is as follows:

1. An inductance system comprising in combination a helix, a pluralityof contact elements associated with said helix, a connection from theelectrical center of said helix to said contacts and means forsimultaneously moving said contact elements in opposite directions andequi-distant from said electrical center.

2. In an inductance system the combination of a helix, contact memberstherefor, said members being electrically connected by a member having asubstantially low inductance, rotatable means for shifting said brushcontact members simultaneously along the lengths of said helix atsubstantially equal rates and in opposite directions with respect to apredetermined point in said helix.

3. An inductance system comprising in combination a helix, a pluralityof contacts associated therewith and electrically connected by a lowinductance member, rotatable means for driving said contactssimultaneously movable to positions along said helix in oppositedirections and e Ill-distant from the original ositions thereo 4. An inuctance system comprising in combination a helix, a plurality of movablecontactors for said helix, an electrical connection from the electricalcenter of said helix to said contactors and means for simultaneouslymoving said contactors in opposite directions and equi-distant from saidelectrical center.

5. In an inductance system the combination of a helix, a connection tothe electrical center of said helix and means for simultaneously shortcircuiting an equivalent number of turns from said electrical centertoward the extremities of said helix,

6. An inductance system comprising in combination a helix adjustableconnecting members engaging the turns of said helix for changing theeffective inductance thereof, said connections being disposed onopposite sides of the electrical center of said inductance, and meansfor sliding said connections in opposite direflkms for simultaneouslyshunting equal values oi inductance from said helix said slidableconnections being connected to the electrical center of said helix,whereby the electrical. equilibrium of said inductance system ismaintained as said slidable connections moved.

7. An inductance system comprising in combination a helix, a pair oi?slidable contactors on said helix disposed symmetrically with referenceto the electrical center thereof, circuits connecting each of saidcontactors to the electrical center of said helix, and means forsimultaneously moving each of said contactors the same distance alongsaid he but in opposite directions, whereby said contactors are at alltimes equidistant from the electrical center of said helix and the LOUISA. GEBHARD.

